Renal cell carcinoma: diffusion-weighted MR imaging for subtype differentiation at 3.0 T

Abstract

Urological Surveying BOO, the positive predict value of others sonographic measurements such detrusor wall thickness (DWT), bladder weight and intravesical prostatic protrusion (IPP) has been investigated. In this study the authors evaluated a group of 100 patients with lower urinary tract symptoms due to benign prostatic hyperplasia. They found that the AUC for IPP was 0.835 with a cutoff of 12 mm having 0.65 sensitivity and 0.77 specificity and 88% positive predictive value. The AUC for DWT was 0.845 and at a 6 mm cutoff they noted 0.73 sensitivity and 0.82 specificity. Patients with 1 of the 2 tests positive (IPP 12 mm or more, or DWT 7 mm or more) have an approximately 90% chance of bladder prostatic obstruction on pressure flow study. In the evaluation of IPP, the authors excluded men with a median lobe, which may cause ball valve type of obstruction and can be easily determined by suprapubic US in the sagittal plane. Special attention was given to the role of protrusion of lateral lobes into the bladder. Radiologists and urologists, who perform urological ultrasound, should be aware of the technical aspects of how to obtain these measurements. The estimative of DWT, is yet the only one of these two parameters which has been recommended by the "American College of Radiology 2008 -Appropriateness Criteria", requires adequate maximum bladder volume, adequate place of the transducer for bladder wall measurement and optimized ultrasound transducer frequency. Radiology, PLA General Hospital, Beijing, China Radiology. 2010; 257: 135-43 Purpose: To assess the usefulness of apparent diffusion coefficients (ADCs) for characterizing renal cell carcinoma (RCC) subtypes at 3.0 T. Materials and Methods: The Institutional Review Board approved this retrospective study, and informed consent was waived. Eighty-three patients underwent diffusion-weighted (DW) magnetic resonance (MR) imaging of 85 renal masses. In each patient, precontrast single-shot spin-echo echo-planar DW imaging was performed with b values of 0 and 500 and 0 and 800 sec/mm(2) by using a 3.0-T MR imaging system. Differences in ADCs between the RCC lesions and uninvolved renal parenchyma were tested by using a paired-samples t test. One-way analysis of variance was used to compare ADCs of the various RCC subtypes. Receiver operating characteristic (ROC) curve analysis was used to test the ability of ADCs in differentiating clear cell from non-clear cell RCCs. Results: Pathologic diagnoses of the 85 tumors (median diameter, 4.4 cm) in the 83 patients (54 men, 29 women; age range, 23-75 years; mean age, 49.4 years) were clear cell RCC for 49 tumors, papillary RCC for 22 tumors, and chromophobic RCC for 14 tumors. With b values of 0 and 500 sec/mm(2), clear cell RCCs showed a significantly higher mean ADC (1.849 × 10(-3) mm(2)/sec) than papillary (1.087 × 10(-3) mm(2)/sec) and chromophobic (1.307 × 10(-3) mm(2)/sec) RCCs (P < .001); however, the difference between papillary and chromophobic RCCs was not significant (P = .068). With b values of 0 and 800...